An optimal-order error estimate for a Galerkin-mixed finite-element time-stepping procedure for porous media flows

2011 ◽  
Vol 28 (2) ◽  
pp. 707-719 ◽  
Author(s):  
Feng-xin Chen ◽  
Huan-zhen Chen ◽  
Hong Wang
2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Dongyang Shi ◽  
Qili Tang ◽  
Yadong Zhang

A characteristic nonconforming mixed finite element method (MFEM) is proposed for the convection-dominated diffusion problem based on a new mixed variational formulation. The optimal order error estimates for both the original variableuand the auxiliary variableσwith respect to the space are obtained by employing some typical characters of the interpolation operator instead of the mixed (or expanded mixed) elliptic projection which is an indispensable tool in the traditional MFEM analysis. At last, we give some numerical results to confirm the theoretical analysis.


Author(s):  
María Eugenia Cejas ◽  
Ricardo Durán ◽  
Mariana Prieto

  We analyze the approximation by mixed finite element methods of solutions of     equations of the form div  [[EQUATION]]  , where the coefficient a=a(x) can     degenerate going to zero or infinity. First, we extend the classic error analysis to this case provided that the     coefficient $a$ belongs to the Muckenhoupt class  [[EQUATION]] .     The analysis developed applies to general mixed finite element spaces satisfying the     standard commutative diagram property, whenever some stability and interpolation     error estimates are valid in weighted norms. Next, we consider in detail the case     of Raviart-Thomas spaces of arbitrary order, obtaining optimal order error estimates for simplicial elements in any dimension and for convex quadrilateral elements in the two dimensional case, in both cases under a regularity assumption on the family of meshes.          For the lowest order case we show that the regularity assumprtion can be removed and prove  anisotropic error estimates which are of interest in problems with boundary layers. Finally we apply the results to a problem arising in the solution of the fractional Laplace equation.


2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Qing-li Zhao ◽  
Zong-cheng Li ◽  
You-zheng Ding

Expanded mixed finite element method is introduced to approximate the two-dimensional Sobolev equation. This formulation expands the standard mixed formulation in the sense that three unknown variables are explicitly treated. Existence and uniqueness of the numerical solution are demonstrated. Optimal order error estimates for both the scalar and two vector functions are established.


2003 ◽  
Vol 3 (1) ◽  
pp. 59-75
Author(s):  
Zhangxin Chen

Abstract In this paper we derive error estimates for finite element approximations for partial differential systems which describe two-phase immiscible flows in porous media. These approximations are based on mixed finite element methods for pressure and velocity and characteristic finite element methods for saturation. Both incompressible and compressible flows are considered. Error estimates of optimal order are obtained.


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